Universal transmit/receive module for radar and communications

ABSTRACT

A universal transmit-receive (UTR) module for phased array systems comprises an antenna element shared for both transmitting and receiving; a transmit path that includes a transmit-path phase shifter, a driver, a switch-mode power amplifier (SMPA) that is configured to be driven by the driver, and a dynamic power supply (DPS) that generates and supplies a DPS voltage to the power supply port of the SMPA; and a receive path that includes a TX/RX switch that determines whether the receive path is electrically connected to or electrically isolated from the antenna element, a bandpass filter (BPF) that aligns with the intended receive frequency and serves to suppress reflected transmit signals and reverse signals, an adjustable-gain low-noise amplifier (LNA), and a receive-path phase shifter. The UTR module is specially designed for operation in phased array systems. The versatility and wideband agility of the UTR module allows a single phased array system to be designed that can be used for multiple purposes, such as, for example, both radar and communications applications.

BACKGROUND OF THE INVENTION

Phased arrays are used in a wide variety of applications. For example,radar phased arrays are used in military aircraft, naval ships, militarysatellites and drone systems to detect, jam, and for missile guidingpurposes. Phased arrays are also used in a large variety of non-militaryapplications including, for example, air and terrestrial trafficdetection and control systems, radio broadcasting, earth-orbitingsatellites, space probe communications, cellular systems, and weatherresearch and forecasting systems. Unfortunately, a single multi-purposephased array system that can be used for all of these different types ofapplications and which can be used for both radar and communicationsapplications, in particular, is not currently available.

A phased array includes a number of spatially separated but proximateantenna elements. The number of antenna elements used depends on theapplication. In principle, a phased array can be made with as few as twoantenna elements. However, the number that is used is usually muchgreater. For example, the FPS-85 radar system in Eglin, Fla. andoperated by the United States Air Force has over 5,000 transmitterantenna elements and nearly 20,000 receive antenna elements.

FIG. 1 is a drawing showing the basic parts of a conventional phasedarray system 100. The phased array system 100 includes a plurality oftransmit-receive (TR) modules, a plurality of associated antennaelements 104, and a beamformer 106. A high-frequency radio frequency(RF) source 108 is also provided, which directs low-power, RF signalsinto the transmit paths of the TR modules 102 during times the TRmodules 102 are transmitting, and a receiver 110 for processing receivedRF signals.

The transmit path in each TR module 102 includes a linear (e.g., ClassA, B, or AB) high-power amplifier (HPA) 112. The receive path in each TRmodule 102 includes a low-noise amplifier (LNA) 114. The antenna element104 associated with each TR module 104 is used for both transmitting andreceiving. When transmitting, low-power RF signals from the RF source108 are directed through the beamformer 106 and amplified intohigh-power RF transmit signals by the HPAs 112. The high-power RFtransmit signals from each TR module 102 are then directed to theantenna elements 104, which convert the high-power RF transmit signalsinto high power electromagnetic waves and radiate the high-powerelectromagnetic waves out over the air or into space where they arereceived by a remote target. When receiving, the antenna elements 104 ofthe phased array system 100 capture electromagnetic energy from incidentelectromagnetic waves and convert the captured electromagnetic energyinto RF electrical signals. Because the electromagnetic energy capturedby the antenna elements 104 is usually very weak, the received RFelectrical signals must be amplified by the LNAs 114 before they can befurther processed downstream. The LNAs 114 are designed for low noisefigure and are incapable of handling high input powers. Accordingly, toprotect the LNAs 114 from being damaged and prevent receiverdesensitization, the received RF signals are first passed throughlimiters 116 before being directed into the inputs of the LNAs 114.

The antenna elements 104 in phased array transceiver systems areconfigured in close proximity so that that the RF power radiated by theantenna elements 104 during transmission can constructively interfereand combine to form a “beam,” and so that the very weak signalsimpinging on the antenna array can be more readily detected. Thebeamformer 106 controls the phase relationships among the transmitted RFsignals in the transmit paths of the TR modules 102 and, consequently,the direction of transmission (or “beam angle”) of the transmitted beam.Depending on the application, the beamformer 106 is configured toestablish a beam with a fixed beam angle or a beam angle that isvariable or adaptive. In applications requiring a fixed beam angle, suchas in a tower array or a geostationary satellite, the antenna array isaimed in the desired direction and the phase relationships among thetransmitted RF signals in the transmit paths of the TR modules 102 areset and fixed to achieve the required fixed beam angle and then notadjusted thereafter. In applications requiring a variable or adaptivebeam angle, such as in radar applications where a target may be moving,the phase relationships of the transmitted RF signals must be varied. Toaccomplish this, the beamformer 106 adjusts and controls the relativetime delays or relative phase shifts of the transmitted RF signals. Byindividually adjusting and controlling the time delays or phase shifts,the transmit beam angle can be varied or, in other words, the transmitbeam can be “steered.” The beamformer 106 may be further configured tocontrol the relative time delays or relative phase shifts of thereceived RF signals passing through the receive paths of the TR modules102. Individually adjusting and controlling the time delays or phaseshifts of the received signals allows the receive array pattern to beadjusted to a desired or required receive array pattern.

One serious and well-known problem associated with TR modules is thatthe RF power generated by the TR module's HPA can be reflected by the TRmodule's antenna element and back into the output of the HPA, instead ofbeing fully radiated by the antenna element. The reflected transmit RFpower is highly undesirable since it can alter the HPA's load impedanceand contribute to intermodulation distortion. Transmitted power can alsobe undesirably reflected from the antenna element and into the receivepath of the TR module, causing distortion of the RF signals beingreceived by the TR module.

Another serious and well-known problem is that when the TR module 102 isconfigured in an array, along with other TR modules (as in FIG. 1), RFsignals transmitted from an antenna element of one TR module can beundesirably intercepted by antenna elements of other TR modules in thearray. These “reverse” signals are also highly undesirable since theycan be passed into the intercepting modules' transmit and receive pathsand cause further distortion in the transmitted and received signals.

In an effort to address these problems, circulators 118 are employed inthe TR modules 102 of conventional phased array systems. As shown inFIG. 1, each of the TR modules 102 is equipped with its own circulator118, and is a three-port device having a first port connected to theoutput of its associated TR module's HPA 112 (transmit path port), asecond port connected to the TR module's antenna element 104 (antennaport), and a third port connected to the input of the receive path ofthe TR module 102 (receive path port). The directional properties of thecirculator 118 are asymmetric (i.e., are non-reciprocal). This asymmetryis exploited and relied on in conventional TR module 102 to preventreflected transmit signals and reverse signals from other TR modulesfrom being directed back into the transmit path and into the output ofthe HPA 112. Specifically when the TR module is transmitting, itscirculator 118 provides a low impedance path for signals directed fromthe circulator's transmit path port to its antenna port, therebyallowing transmitting to occur, but isolates the transmit port from theantenna port in the reverse direction, for example, by attenuatingsignals (such as reflected signals or reverse signals) flowing in thereverse direction.

Although the circulators 118 can be effective, they do not provide anyprotection for signals that are reflected into the receive path of theTR module and do not provide protection against reverse signals fromother TR modules in the array from being directed into the receive path.Furthermore, the circulators 118 are effective at preventing transmitreflected signals and reverse signals into the transmit path only over avery narrow range of operating frequencies. This narrowband limitationis highlighted in FIGS. 2A and 2B, which are scattering parametermeasurements taken on a typical circulator. FIG. 2A shows the forwardtransfer coefficient (scattering parameter (S-parameter) S21) of thecirculator swept over a 900 MHz to 1 GHz frequency range. FIG. 2B showsthe reverse transfer coefficient (S-parameter S12) of the circulatorswept over the same frequency range. As can be seen in FIG. 2A, theforward transfer coefficient S21 remains flat and near 0 dB (˜−0.27 dB)over the entire swept frequency range, indicating that for the forwarddirection, if the circulator was to serve as one of the circulators 118in one of the TR modules 102 of the phased array system 100 in FIG. 1,it would be effective at delivering most of the power from port 1(attached to transmit path port) to port 2 (attached to antenna port).However, FIG. 2B reveals that the reverse transfer coefficient S12provides high isolation in the reverse direction only over a very narrowisolation band of ˜30 MHz. The very narrow isolation band means that ifthe circulator was to serve as one of the circulators 118 in one of theTR modules 102 of the phased array system 100 in FIG. 1, transmitted RFsignals outside the isolation band would be susceptible to beingreflected by the TR module's antenna element 104 back into the transmitpath of the TR module 102.

Circulators must be used in conventional phased array systems in orderto prevent transmit signals and reverse signals from reflecting backinto the transmit paths of the TR modules 102. However, the presence ofthe circulators 118 and their narrowband limitations precludes theconventional phased array system 100 from being used in any applicationexcept for the specific application for which it is designed. In otherwords, conventional phased array systems are not multi-purpose andcannot be used for multiple applications, such as for both radar andcommunications applications, for example.

In addition to the narrowband restrictions imposed by the circulators118, the circulator 118 does not do anything to prevent reflectedtransmit signals from being directed into the receive path of a TRmodule 102, and does not do anything to prevent reverse signals fromother TR modules 102 from being directed into TR module's receive path.The receive signals are therefore susceptible to being distorted bytransmit reflected signals and reverse signals from other TR modules.

Other drawbacks associated with circulators are that they are largepassive devices that have insertion losses, consume power, occupy largeareas of the printed circuit board (PCB) on which they and the othercomponents of the TR modules 102 are formed, and contribute to theoverall weight and size of the phased array system 100. As can be seenin FIG. 3, which is a photograph of a typical conventional TR module300, the circulator 304 and associated PCB waveguide traces occupynearly a third of the area of the PCB 302. Moreover, because the HPA 112of the TR modules 102 is a linear amplifier, it is large in size andvery inefficient. Due to its inefficiency, a very large heatsink 306(see FIG. 3) is required to conduct heat away from the HPA 112 and toprotect the HPA 112 from being damaged, and a larger power supply thandesired is necessary to compensate for the HPA's inefficiency. The largecirculator 304 and large heatsink 306 also add to the cost, size andweight of the TR module 102. Because phased array systems will ofteninclude hundreds and sometimes thousands of TR modules 102, theincremental cost, size and weight of each TR module 102 must bemultiplied by hundreds or thousands of times in determining the overallcost, size and weight of the entire system. Furthermore, with hundredsand possibly thousands of very inefficient HPAs 112, large and heavypower supplies are required to compensate for the multipleinefficiencies and very large and heavy cooling systems are necessary todisplace the enormous amount of heat generated by the hundreds andpossibly thousands of HPAs 112.

BRIEF SUMMARY OF THE INVENTION

Transmit-receive (TR) modules for radar and communications phased arraysystems and methods are disclosed. An exemplary TR module includes atransmit path, a receive path, and an antenna element that is shared bythe transmit path and receive path. The transmit path includes atransmit-path phase shifter, a driver, a switch-mode power amplifier(SMPA), and a dynamic power supply (DPS) that generates a DPS voltage.The receive path includes a transmit/receive (TX/RX) switch, a bandpassfilter (BPF), an adjustable-gain low-noise amplifier (LNA), and areceive-path phase shifter

When configured in a phased array, the transmit-path phase shifters inthe UTR modules of the array individually introduce unique phase shiftsin a plurality of low-power RF transmit signals that are being directedalong their associated transmit paths. The phase shifts introduced bythe transmit-path phase shifters collectively determine the direction oftransmission of the final high-power transmit beam that is ultimatelyproduced by the array. The transmit-path phase shifters can also bedynamically adjusted, thereby allowing the beam to be steered. Thedrivers in the UTR modules drive the RF input ports of their SMPAs,according to the phase-shifted low-power RF transmit signals, and whilethe DPS voltages are applied to the power supply ports of the SMPAs. TheSMPAs are switched ON and OFF by the driver, between compressed andcut-off states. The DPS voltages are used to set and control the RFoutput powers of the SMPAs. They can also be independently controlled,in order to affect the aperture profile of the final transmit beam.Depending on the application, the DPS voltages may be further varied tocontrol the signal envelope of the high-power RF signals produced by theSMPAs. Finally, the antenna elements of the UTR modules transduce thehigh-power RF signals produced by the SMPAs into high-power RFelectromagnetic waves and radiate the resulting high-power RFelectromagnetic waves into the air or space, where they interfere andcombine to form the desired high-power transmit beam, which depending onthe application (for example, radar or communications), is directedtoward a remote target or remote receiver. In applications in which thelocation of the target or remote receiver is unknown, the UTR modulescan be physically arranged (e.g., spherically or in some othermulti-dimensional spatial configuration) and/or the transmit beamdirection can be electronically controlled to produce a transmit beamthat is omni-directional, quasi-omni-directional, isotropic, orquasi-isotropic, thereby allowing the array beam to be radiatedomni-directionally, quasi-omni-directionally, isotropically, orquasi-isotropically and the transmitted beam to therefore arrive at thetarget or remote receiver despite the location of the target or remotereceiver being unknown.

When the phased array system is receiving, RF electromagnetic wavesincident on the antenna elements of the array (for example, RFelectromagnetic radar pulses that arriving after being reflected from aremote target (radar application) or RF electromagnetic communicationswaves arriving from a remote transmitter (communications application))are transduced by the antenna elements, thereby forming a plurality oflow-power RF receive signals. The low-power RF receive signals aredirected into the receive paths of the UTR modules and introduced to theBPFs. The BPFs are tuned (either beforehand or dynamically) to theintended frequency of the low-power RF receive signals. Each BPF alsoserves to suppress any transmit RF signals that may be reflected intothe receive path and any unwanted reverse signals that may beintercepted by the antenna element from other UTR modules, therebyprotecting the low-power RF receive signals from being distorted. Thefiltered low-power RF receive signals are then amplified by theiradjustable-gain LNAs and phase-shifted by the receive-path phaseshifters if desired or needed to adjust the receive array pattern, anddownconverted (and demodulated, if need be) to baseband signals.Finally, the baseband signals are combined to form the desired receivesignal.

Further features and advantages of the invention, including a detaileddescription of the above-summarized and other exemplary embodiments ofthe invention, will now be described in detail with respect to theaccompanying drawings, in which like reference numbers are used toindicate identical or functionally similar elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing the basic parts of a conventional phasedarray system;

FIGS. 2A and 2B are screen shot measurements of the forward transfercoefficient S21 of a typical circulator (FIG. 2A) used in conventionaltransmit-receive (TR) modules and the reverse transfer coefficient S12of the same circulator;

FIG. 3 is a reproduction of a photographic of a TR module commonly usedin conventional phased array systems;

FIG. 4 is a drawing of a universal transmit-receive (UTR) module,according to an embodiment of the present invention, highlighting theUTR module's salient components;

FIG. 5 is a schematic diagram of an exemplary gallium-nitride based(GaN-based) driver and GaN-based switch-mode power amplifier (SMPA),which can be used to implement the SMPA in the UTR module in FIG. 4, inaccordance with one embodiment of the present invention;

FIG. 6 is a simplified schematic diagram of a linear-regulator-baseddynamic power supply (DPS), which can be used or modified to implementthe DPS in the transmit path of the UTR module in FIG. 4, in accordancewith one embodiment of the invention;

FIG. 7 is a simplified schematic diagram of a switch-based Class-Smodulator, which can be used or modified to implement the DPS in thetransmit path of the UTR module in FIG. 4, in accordance with oneembodiment of the invention;

FIG. 8 is a drawing of the UTR module 400 in FIG. 4, provided toillustrate that in a preferred embodiment of the invention, the variouscomponents of the UTR module in FIG. 4 are mounted on a printed circuitboard (PCB);

FIG. 9 is a graph showing the phase stiffness characteristics of theSMPA of the UTR module in FIG. 4, highlighting the SMPA's superior phasestiffness characteristics;

FIG. 10 is graph showing the total amplifier efficiency (TAE) of theSMPA of the UTR module in FIG. 4, the TAE of the entire transmitter ofthe UTR module in FIG. 4, and the TAE of the transmitters used in threedifferent prior art TR modules that employ linear HPAs;

FIG. 11 is a graph showing the required power supply size and heatsinksize for a high-power power amplifier when configured in a TR moduleversus the efficiency of the high-power power amplifier (horizontalaxis) and normalized power (vertical axis);

FIG. 12 is a drawing provided to illustrate how the UTR module in FIG. 4can be configured for operation in a full-duplex communications system;

FIG. 13 is a drawing provided to illustrate how the UTR module in FIG. 4can be configured for operation in a communications system that uses thetime division multiple access (TDMA) channel access method;

FIG. 14 is a system level drawing of a communications phased arraysystem, according to an embodiment of the present invention;

FIG. 15 is a system level drawing of a communications phased arraysystem, according to an embodiment of the present invention;

FIG. 16 is a system level drawing of a communications phased arraysystem, according to an embodiment of the present invention;

FIG. 17 is a drawing showing the salient elements of a direct digitalsynthesizer (DDS) that can be used, modified or adapted to producephase-modulated RF signals for the various communications phased arraysystems of the present invention;

FIG. 18 is a system level drawing of a communications phased arraysystem, according to an embodiment of the present invention;

FIG. 19 is a system level drawing of a communications phased arraysystem, according to an embodiment of the present invention;

FIG. 20 is a drawing of a multi-purpose communications phased arraysystem, according to an embodiment of the present invention;

FIG. 21 is a drawing provided to illustrate how the UTR module in FIG. 4can be configured for use in a radar phased array;

FIG. 22 is a system level of a radar phased array system, according toan embodiment of the present invention;

FIG. 23 is a system level drawing of a radar phased array system,according to an embodiment of the present invention;

FIG. 24 is a drawing of a multi-purpose radar phased array system,according to an embodiment of the present invention;

FIG. 25 is a system level drawing of a multi-purpose phased array systemthat can be used for both radar and communications applications,according to an embodiment of the present invention; and

FIG. 26 is a system level drawing of a multi-purpose phased array systemthat can be used for both radar and communications applications,according to an embodiment of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 4, there is shown a transmit-receive (TR) module 400for use in phased array systems, including radar phased array systemsand communications phased array systems. By virtue of its versatility,wideband agility, and multi-purpose capabilities, the TR module 400 isreferred to in the detailed description that follows as a “universal TRmodule” or “UTR module.”

The UTR module 400 includes a transmit path 402, a receive path 404, andan antenna element 406 that is shared by the transmit and receive paths404 and 406. The transmit path 402 includes a power amplifier (PA),preferably a switch-mode power amplifier (SMPA) 408, having an outputthat is directly coupled (direct connection or via an AC couplingcapacitor) to the antenna element 406, for example, via a low-loss(e.g., 50Ω) path; a driver 410 that is configured to drive the SMPA 408;a dynamic power supply (DPS) 412 and a transmit-path phase shifter 414(or adjustable time delay device). The receive path 404 includes atransmit/receive (TX/RX) switch 416, a tunable band-pass filter (BPF)418, a low-noise amplifier (LNA) 420, and a receive-path phase shifter422 (or adjustable time delay device). Each of the various elements ofthe UTR module 400 is discussed in further detail below.

The transmit-path shifter 414 is used to introduce a phase shift in theRF signal transmitted through the transmit path 402 of the UTR module400. Similarly, the receive-path phase shifter 422 is used to introducea phase shift in the RF signal transmitted through the receive path 404.The transmit-path and receive-path phase shifter 414 and 422 may beimplemented as either fixed or adjustable phase shifters, but arepreferably made to be adjustable, so that the UTR module 400 can be usedin electronically scanned phased array systems. They may also be activeor passive, and digital or analog. For example, in one embodiment ofinvention, the transmit-path and receive-path phase shifters 414 and 422are active phase devices implemented in a single or separate monolithicmicrowave integrated circuit (MMIC) that is/are made from galliumarsenide GaAs field-effect transistors (GaAs-FETs) or gallium nitrideFETs (GaN-FETs) and mounted on a printed circuit board (PCB), along withthe other components of the UTR module 400. In another embodiment of theinvention, the transmit-path and receive-path phase shifters 414 and 422are passive devices such as, for example, micromechanical (MEM) devicesor other passive devices having capacitors and/or inductors which maybe, though not necessarily, etched into one or more conducting layers ofthe UTR module's PCB.

The SMPA 408 and driver 410 in the transmit path 402 of the UTR module400 may also be implemented in various ways. FIG. 5 shows an exemplarygallium-nitride (GaN)-based driver 410 and GaN-based SMPA 408, which maybe used or adapted for use in UTR module 400. The GaN-based SMPA 408 andGaN-based driver 410 are preferably designed and manufactured in anintegrated circuit (IC) chip using GaN high electron mobilitytransistors (GaN-HEMTs). However, other solid-state switching devicesmade of the same or other types of semiconducting materials may bealternatively used, as will be appreciated by those of ordinary skill inthe art. The GaN-based driver 410 includes first and second GaN-HEMTs502 and 504. The drain of the first GaN-HEMT 502 is connected to a drainsupply voltage VDD1, and the source of the second GaN-HEMT 504 isconnected to a more negative source supply voltage VSS1. AC couplingcapacitors 506 and 508 are coupled between the gates of the first andsecond GaN-HEMTs 502 and 504 and first and second input terminals 510and 512. The first and second input terminals 510 and 512 are configuredto receive first and second RF input signals RFin and RFin, which are180 degrees out of phase First and second DC bias resistors 514 and 516are also connected to the gates of the first and second GaN-HEMTs 502and 504, and serve to set the DC operating points of the first andsecond GaN-HEMTs 502 and 504. Finally, an inductor 518 is connectedbetween a second drain supply voltage VDD2 and the output of the driver410. It should be noted that whereas the inductor 518 is shown to beconfigured to receive a first supply voltage VDD1 different from thesecond supply voltage VDD2 applied to the drain of the first GaN-HEMT502, the inductor 518 and first GaN-HEMT 502 can be alternativelyconfigured to share the same power supply. Additionally, the firstGaN-HEMT 502 (and possibly the inductor 518) and high-power GaN-HEMT 522in the GaN-based SMPA 408 can be configured to share the DPS voltagegenerated and provided by the DPS 412, as illustrated in FIG. 4.

The output of the GaN-based driver 410 is coupled to the input of theGaN-based SMPA 408, via an AC coupling capacitor 520. The GaN-based SMPA408 includes a high-power n-channel depletion mode GaN-HEMT 522, whichis configured to operate as a switch and generate high RF power for theUTR module's 400 antenna element 406. A DC bias resistor 524 isconnected to the gate of the high-power GaN-HEMT 522, and serves to setthe DC operating point of the high-power GaN-HEMT 522. Finally, aninductor 526, which receives the DPS voltage from the DPS 412, isconnected to the drain of the high-power GaN-HEMT 522.

During operation, when the first GaN-HEMT 502 is turned on and thesecond GaN-HEMT 504 is turned off, the first GaN-HEMT 502 pulls the gateof the high-power GaN-HEMT 522 in the GaN-based SMPA 408 up to the drainsupply voltage VDD1, causing the high-power GaN-HEMT 522 to switch on.As the high-power GaN-HEMT 502 is being turned on, the inductor 518 inthe GaN-based driver 410 serves as a current source that supplies acurrent I_(L). The inductor current I_(L) combines with the currentI_(DD) being supplied through the first GaN-HEMT 502, thereby enhancingthe current flow into the gate of the high-power GaN-HEMT 522 to shortenthe turn on time of the high-power GaN-HEMT 522. Enhancing current flowin this way allows the GaN-based SMPA 408 to operate at very high RFfrequencies. Conversely, when the first GaN-HEMT 502 is turned off andthe second GaN-HEMT 504 is turned on, the gate of the high-powerGaN-HEMT 522 is pulled down to the source supply voltage VSS1 applied tothe source of the second GaN-HEMT 504, causing the high-power GaN-HEMT522 in the GaN-based SMPA 408 to switch off Because the high-powerGaN-HEMT 522 dissipates power only during the times it is beingswitched, the GaN based SMPA 408 is very energy efficient. Efficiency isfurther enhanced by powering the GaN-based SMPA 408 using the DPSvoltage provided by the DPS 412. Further details of the GaN-based SMPA408 and GaN-based driver 410 may be found in commonly owned and assignedU.S. patent application Ser. No. 14/743,046, entitled “Current EnhancedDriver for High-Power Solid-State Radio Frequency Power Amplifiers,”which is incorporated herein by reference. Commonly owned and assignedU.S. patent application Ser. No. 14/447,452, entitled “Limiting Driverfor Switch-Mode Power Amplifier,” also discloses a driver, SMPA andsignal conditioning circuitry that may be used to implement, modify orsupplement the GaN-based SMPA 408 and GaN-based driver 410. Thatapplication is also incorporated herein by reference.

The DPS 412 in the transmit path 402 of the UTR module 400 is configuredto produce a DPS voltage that depends on a DPS control signal applied tothe control terminal ρ of the DPS 412. As will be discussed in furtherdetail below, the UTR module 400 may be used in a phased array systemthat can be used for both radar and communications, either alternatelyor simultaneously. Accordingly, depending on the application, inaddition to controlling the RF output power produced by the SMPA 408,the DPS control signal may be also used to set and control envelopevariations (information-bearing or non-information-bearing) in thehigh-power, high-frequency RF signal transmitted by the UTR modules 400.In radar applications the DPS control signal can also be used to affectthe aperture profile of the transmitted radar beam. In some applicationsthe location of the target or remote receiver may be unknown. In thoseapplications the UTR modules 400 making up the phased array system canbe physically arranged (e.g., spherically or in some othermulti-dimensional spatial configuration) and/or the transmit beamdirection can be electronically controlled to produce a transmit beamthat is omni-directional, quasi-omni-directional, isotropic, orquasi-isotropic, thereby allowing the array beam to be radiatedomni-directionally, quasi-omni-directionally, isotropically, orquasi-isotropically and the transmitted beam to therefore arrive at thetarget or remote receiver despite the location of the target or remotereceiver being unknown.

The DPS 412 can be, but is not necessarily, fabricated in the same ICchip as the driver 410 and SMPA 408. It can also be designed in variousways. FIG. 6 illustrates, for example, how the DPS 412 can be designedbased on a linear voltage regulator 602. According to this approach, thelinear regulator 602 controls the on resistance of a field-effecttransistor (FET) 604 based on the DPS control signal applied to thecontrol input ρ of the linear regulator 602. Because power lossaccording to this approach is directly proportional to the voltage dropVdrop across the FET 604, this approach to implementing the DPS 412 maynot be the most attractive approach. Nevertheless, if efficiency is nota concern, the linear voltage regulator approach can provide a simple,low-cost solution.

In most phased array applications efficiency is a primary concern,however. Therefore, to maximize efficiency, the DPS 412 is preferablydesigned using some type of switch-based modulator. FIG. 7 is a drawingillustrating how the DPS 412 can be constructed using a Class-Smodulator 702. According to this approach, a transistor 704 and diode706 are configured as a two-pole switch, which is controlled by apulse-width modulation (PWM) driver 708. The widths of the pulses in thePWM drive signal provided by the PWM driver 708 are varied to controlthe on/off status of the switching transistor 704, in accordance withthe DPS control signal applied to the control input p. The output LCfilter 710 filters the output of the two-pole switch to recover thedesired DSP supply voltage, as directed by the DPS control signal. TheClass-S modulator 702 is substantially more efficient than the linearregulator approach in FIG. 6. Accordingly, it 702 or some other type ofswitch-based modulator is preferably used to implement the DPS 412.

The TX/RX switch 416 in the receive path 404 of the UTR module 400operates depending on the application, and its control and operation aredescribed in further detail below.

The BPF 418 serves to filter the RF signal received by the antennaelement 406 and is preferably, though not necessarily, tunable, so thatBPF 418 can be tuned to the intended RX frequency band. It should bementioned that, although only a single BPF 418 is shown to be present inthe exemplary UTR module 400 in FIG. 4, it is possible to includeseveral BPFs having different bandpass characteristics and/or tuningcapabilities in the UTR module 400.

Finally, the LNA 420, which preferably has an adjustable gain G, servesto amplify the BPF-filtered signal produced at the output of the BPF418.

The various components of the UTR module 400 are preferably mounted on aPCB 802, as illustrated in FIG. 8. The PCB 802 includes, in addition tothe transmit and receive path components, conducting traces (not shown)on either or both sides of the PCB 802 or, alternatively, in variousconducting layers laminated in the PCB 802. The conducting tracesprovide the electrical connections that electrically connect the variouscomponents of the UTR module 400 to one another. To support highfrequency applications, some or all of the conducting traces may beimplemented as microstrip or stripline transmission lines, which serveas high-frequency waveguides. Note that the various components of theUTR module 400 need not be arranged in the positions shown in the FIG.8, and are not drawn to scale. The drawing is provided to merelyemphasize that in a preferred embodiment of the invention the variouscomponents of the UTR module 400 are mounted, in some way, on a PCB 802.In addition to the components of the UTR module 400 shown in FIG. 4, oneor more DC power supply chips 804 may be mounted on the PCB 802 tosupply DC power to the UTR module components. Alternatively oradditionally, one or more alternative or additional external DC powersupplies can be used to supply DC power to the components on the PCB 802that require DC power. The PCB 802 further includes input/output (I/O)terminals 806 and 808 for inputting/outputting the RF transmit andreceive signals, which depending on the application, may or may not bemodulated with information. The array control terminals include firstand second phase-adjust input terminals 810 and 812 that are configuredto receive transmit-path and receive-path phase shift control signalsφ_(TX) and φ_(RX) for setting and controlling the phase shifts Δφ_(TX)and Δφ_(RX) of the transmit-path and receive-path phase shifters 414 and422, a gain input terminal 814 configured to receive a gain controlsignal that sets and controls the gain G of the LNA 420, and a DPScontrol terminal 816 that is configured to receive the DPS controlsignal for the control input ρ of the DPS 412. The PCB 802 may furtherinclude an antenna element connector port 818 for receiving the UTRmodule's antenna element 406. Alternatively, the antenna element 406 canbe permanently attached to the PCB 802 or formed on or as part of thePCB 802 itself.

One significant advantage of the UTR module 400 over conventional TRmodules (such as the conventional TR modules 102 described in FIG. 1above) is that the UTR module 400 does not require a circulator. Infact, the output of the transmit path (i.e., the output of the SMPA 408)can be configured to remain directly coupled (e.g., by direct physicalconnection or via an AC coupling capacitor) to its respective antennaelement 406 at all times. A circulator is unnecessary, even for widebandoperations, due to the unique design and configuration of the UTR module400. Among other characteristics, the presence and configuration of theSMPA 408, the configuration and operation of the TX/RX switch 416, andthe tunability of the BPF 418 all contribute to the versatility andwideband capability of the UTR module 400. Unlike the linear HPAs 112used in conventional TR modules, the SMPA 408 in the UTR module 400 is“phase stiff” meaning that it is significantly better at toleratingreverse and reflected signals than are linear HPAs. FIG. 9 is a graphthat highlights this phase stiffness superiority of the SMPA 408 overtwo types of linear HPAs often used in conventional TR modules: aClass-A HPA and a Class-AB HPA. The measurements in the graph comparethe absolute value of the output-reflection coefficient (i.e.,S-parameter |S22|) of the Class-A and Class-AB HPAs compared to |S22| ofa single-ended (SE) SMPA (like the SE GaN-based SMPA 408 in FIG. 5),when a disturbing signal (e.g., a reflected or reverse signal) isdirected into the outputs of the various PAs. The Class-A and Class-ABHPAs are seen to be 7 to 10 dB less tolerant to the disturbing signalover the entire range of applied disturbing signal strengths (−25 dB to0 dB). In other words, the SMPA is about 80% less sensitive to reversesignals than are the Class-A and Class-AB HPAs. Due to the superiorphase stiffness of the SMPA 408, the SMPA 408 is able to tolerate anyreflected or reverse signals that may be directed into the output of theSMPA 408 and produce a transmit signal that has not been distorted bythe reflected and reverse signals.

The need for a circulator to isolate the receive path 404 is alsoeliminated by virtue of the presence of the TX/RX switch 416 and the BPF418 in the receive path 416. In one embodiment of the invention the BPF418 is tunable, thus allowing it to be tuned to align with the RX signalfrequency. The filter skirts of the tuned BPF 418 suppress any TXsignals that might be reflected from the antenna element 406 and anyreverse signals that may be intercepted by the antenna element 406 fromother UTR modules, thereby preventing the reflected and reverse signalsfrom being directed into the LNA 420 while still allowing the desired RXsignal to pass through to the LNA 420.

Another very important advantage of the UTR module 400 over conventionalTR modules is that the UTR module 400 is extremely energy efficient. Theenergy efficiency of an electrical system provides an indication of howeffective the system is at converting electrical power supplied to itinto useful power. Power that is not used is undesirably dissipated asheat. FIG. 10 is a graph showing the total amplifier efficiency (TAE)(TAE (%)=100×Pout/(Pin+Pdc)) of the SMPA 408 by itself (arrow labeled“1002”) and the TAE of the entire transmit path 402 of the UTR module400 (arrow labeled “1004”) over a frequency range of about 200 MHz toabout 3 GHz, where Pdc is the DC power supplied, Pin is the RF inputpower, and Pout is the RF output power (i.e., useful power) produced atthe output of the SMPA 408. The TAE of the SMPA 408 by itself (arrow1002) is seen to be very high (about 70%) and over the entire 200 MHz to3 GHz frequency range. The TAE of the entire transmit path 402 is, ofcourse, lower than the TAE of the SMPA 408 by itself, but is also veryhigh and approximately 55% over the entire 200 MHz-3 GHz frequencyrange.

FIG. 10 also includes the TAE performance of transmitters employed inthree different prior art TR modules (indicated by the arrows labeled“1006”, “1008” and “1010”). The TAE of the transmitters in all threeprior art modules is seen to be substantially lower than both the TAE ofthe SMPA 408 by itself (arrow 1002) and the TAE of the entire transmitpath 402 of the UTR module 400 (arrow 1004). In particular, the TAE ofthe transmitter of the first prior art TR module (arrow 1006) is onlyabout 35%; the TAE of the transmitter of the second prior art TR module(arrow 1008) is less than 20%; and the TAE of the transmitter of thethird TR module (arrow 1010) is less than 2%. The low TAEs of thetransmitters in the first, second, and third prior art TR modules is dueprimarily to the fact that they employ linear HPAs in theirtransmitters.

The graph in FIG. 10 also highlights that the first and second prior artTR modules (arrows 1006 and 1008) are capable of operating only verynarrow frequency ranges. This narrowband restriction is due to thepresence of the circulators employed in those two TR modules. Incontrast, the SMPA 408 (and, correspondingly, the UTR module 400 of thepresent invention overall) is seen to operate efficiently over a wideband of frequencies, even exhibiting over a decade bandwidth capability(i.e., fmax/fmin≈200 MHz/3 GHz>10). The third TR module (arrow 1010)does not employ a circulator, and is seen to be capable of operatingover a wide frequency range. However, because it too employs a linearHPA in its transmitter and has a TAE of less than 2%, it is unsuitablefor most purposes and especially unsuitable for use in phased arraysystems in which very high RF output powers must be produced.

The superior efficiency the SMPA 408 also allows a much smaller heatsink820 (see FIG. 8) to be used, compared to the size of the heatsink thatis required for a linear HPA producing the same useable RF output power.FIG. 11 is a graph showing the power supply size and heatsink sizerequired for a high-power PA configured in a TR module versus theefficiency of the high-power PA (horizontal axis) and normalized power(vertical axis). At the point where the heatsink size curve intersectsthe 50% efficiency and unity normalized power crossing, the heatsink ofthat size absorbs the same amount of power as is delivered to the TRmodule's antenna element. However, when the high-power PA is less than30% efficient, it is seen that the heatsink must be of a size that iscapable of absorbing more than double the power delivered to the antennaelement, and the power supply size must be at least twice as large asthat which can be used when the high-power PA is 50% efficient.Considering the superior efficiency of the SMPA 408 in the UTR module400 compared to the relative inefficiencies of the linear HPAs used inprior art TR modules (see, for example, FIG. 10 above), the heatsinksize required for the SMPA 408 can be between ⅓ to 1/7 the size of theheatsink that would be required for a linear HPA producing the sameuseable RF output power.

Eliminating the need for a circulator and employing an SMPA 408 in theUTR module 400 allows a phased array system to be constructed that has asubstantially better SWaP (size, weight and power) performance than canbe possibly realized in phased array systems employing conventional TRmodules. Phased array systems will often employ hundreds and sometimesthousands of TR modules. Accordingly, the SWaP performance of each TRmodule is a major factor in determining the SWaP performance of thephased array system as a whole. Since the UTR module 400 of the presentinvention can operate effectively, over wide frequency ranges andwithout using a circulator, and can use a much smaller heatsink for theSMPA 408, the UTR module 400 can be made much smaller and much lighterthan conventional TR modules. The wideband agility of the UTR module 400can be further enhanced, and the size and weight of the UTR module 400can be further reduced, by implementing the SMPA 408 and driver 410 as aGaN-based IC (for example, as explained above in reference to FIG. 5).GaN has a high power density, thus allowing the GaN-based driver 410 andGaN-based SMPA 408 (see FIG. 5) to be fabricated in a compact IC and tobe packaged in a small form factor. Loading of electrical power deliverysystems is also significantly reduced when the UTR modules 400 are usedin phased arrays, since the energy needed to power the phased array issubstantially less than required by conventional phased array systemsemploying conventional TR modules. Finally, the superior efficiency ofthe UTR modules 400 allows much smaller and lighter power supplies to beused to power the phased arrays and minimizes the size and weight offans and other cooling systems that may be needed to displace the heatgenerated by the UTR modules 400.

In addition to its superior SWaP characteristic, the UTR module 400 isvery versatile. For example, a plurality of UTR modules 400 can bedeployed in radar phased arrays (narrowband or wideband), incommunications phased arrays, or even in a single phased array systemthat can be used alternately or simultaneously for both radar andcommunications. The UTR modules 400 can also be easily manipulated andconfigured for operation in half-duplex, full-duplex andfull-duplex-like systems, even on-the-fly, according to differentchannel access methods (e.g., time division multiple access (TDMA), codedivision multiple access (CDMA), space division multiple access (SDMA),etc.), and according to different communications standards that requiredifferent modulation formats. FIG. 12 illustrates, for example, how aUTR module 400 can be configured for operation in a full-duplexcommunications system, such as in frequency division duplex (FDD)communications. In a full-duplex system, transmitting and receivingoccur simultaneously. To support simultaneous transmission andreception, the TX/RX switch 416 of the UTR module 400 is therefore setto the RX position at all times. The DPS 412 sets the TX power andsignal envelope variations in the RF TX signal produced at the output ofthe SMPA 402, in accordance with the DPS control signal applied to thecontrol input ρ of the DPS 412. The phase shift Δφ_(TX) introduced intothe transmit path 402 by the transmit-path phase shifter 414 is set andcontrolled by a transmit path phase-shift control signal φ_(TX) appliedto the phase control input of the transmit-path phase shifter 414. Whenthe UTR module 400 is deployed in a communications phased array system,the phase shifts introduced into the transmit paths 404 by thetransmit-path phase shifters 414 in the other UTR modules 400 of thearray are also individually set and controlled, so that collectively thephase shifts introduced into the transmit paths 402 of the UTR modules400 in the array define the transmit beam angle. If directedcommunications is being used, the transmit path phase-shift controlsignal applied to the transmit-path phase shifters 414 in each UTRmodule can also be used to individually and dynamically adjust the phaseshift introduced into each of the transmit paths 402 of the UTR modules400, thereby allowing the communications transmit beam produced by thearray to be steered. The phase shift Δφ_(RX) introduced into the receivepath 404 by the receive-path phase shifter 422 is set and controlled bythe receive-path phase-shift control signal φ_(TX) applied the phasecontrol input of the receive-path phase shifter 422. When the UTR module400 is deployed in communications phased array system, the phase shiftsintroduced by the receive-path phase shifters 422 in the receive paths404 of the other UTR modules 400 in the array are also individually setand controlled, so that collectively the phase shifts introduced intothe receive-paths 404 of the array's UTR modules 400 define the receivearray pattern. The receive path phase-shift control signals applied tothe receive-path phase shifter 422 in the array's UTR modules 400 canalso be individually and dynamically adjusted during receiving, allowingthe received array pattern to be dynamically varied and therebyestablishing a desired or required receive array pattern. The LNAs 420in the receive paths 404 of the UTR modules 400 also have gain controlinputs which allow their gains G to be individually and dynamicallyadjusted, in order to further affect the receive array pattern. Finally,the BPF 418 in the receive path 404 of the UTR module 400 is tunable, sothat it and the other UTR modules 400 in the array can be tuned to theintended RX frequency. The filter skirts of the BPF 418 also suppress(i.e., filters out) any transmitted signals that might be reflected fromthe UTR module's antenna element 406 and into the receive path 404 and,when the UTR module 400 is deployed in an array, suppresses reversesignals transmitted by other UTR modules in the array that may beundesirably captured by the antenna element 406 of the UTR module 400and directed into the receive path 404, thereby protecting the LNA 420of the UTR module 400 from being damaged and preventing the reflectedand reverse signals from distorting the desired receive signal.

The ability to dynamically tune the BPF 418 in the receive path of theUTR module 400 together with the superior phase stiffness of the SMPA408 allow a phased array system that is FDD-capable to be constructedwhich has a number of performance advantages over an FDD-capable phasedarray system constructed from conventional TR modules. For example,constructing an FDD-capable phased array system using the UTR modules400 has a substantially higher capacity than what can be achieved in anFDD-capable phased array system constructed from conventional TRmodules. In conventional TR modules a circulator or a duplexer must beemployed to support full-duplex operation and to suppress, to the extentthat either is capable, reflected and reverse signals. However, sincethe circulator and duplexer are restricted to the TX and RX bands forwhich they are designed and are not adjustable, the ability to suppressreflected and reverse signals is extremely limited and altogetherineffective if FDD operations are to be performed. This constraint,along with the fact that the HPAs in conventional TR modules are linearamplifiers with low phase stiffness, means that for any practicalapplication the only way to construct an FDD-capable phased array systemusing conventional TR modules is to partition the conventional TRmodules so that, for each TX band involved, a first set of conventionalTR modules is specifically dedicated for that TX band and, for each RXband that is involved, a second set of conventional TR modules isspecifically dedicated for that RX band. In contrast, the UTR module 400of the present invention does not require either a circulator or aduplexer to suppress reflected and reverse signals. The SMPA 408 isphase-stiff, making it much less affected by reflected and reversesignals than the linear HPA in conventional TR modules. Furthermore,when configured in an array that is FDD-capable, the high phasestiffness property of the SMPA 408 prevents reflected and reversesignals from degrading the transmission characteristics of the UTRmodules 400, and the ability of the BPF 418 to be dynamically tuned overa wide range of RX band frequencies prevents reflected and reversesignals from being introduced into the LNAs 420 of the UTR modules 400.Since there is no need to partition the UTR modules 400 in the array sothat some are used only for transmitting and others are used only forreceiving, the capacity of the system is therefore superior to anyFDD-capable phased array system constructed from conventional TRmodules.

The ability to dynamically adjust the BPF 418 in each UTR module 400further results in a lower noise floor than can be achieved in anFDD-capable phased array system constructed from conventional TRmodules. When using the UTR modules 400 to construct an FDD-capablephased array system, all of the UTR modules 400 making up the array canbe dynamically adjusted from one RX band to another on-the-fly. Sincethe receive paths of conventional TR modules cannot be tuned todifferent RX bands, let alone dynamically and on-the-fly, and becausethe conventional TR modules making up the array must be partitioned inorder to support FDD operations, the noise floor of a conventionalphased array system constructed using conventional TR modules isnecessarily higher than the noise floor in a phased array systemconstructed using the UTR modules 400 of the present invention. Thereason for the higher noise floor is that when a system divides its TRmodules over multiple RX bands, the minimum noise floor that isachievable is determined by the sum of the noise in each RX band. Sincethe noise floor in a phased array system constructed from conventionalTR modules is higher in a phased array system constructed using the UTRmodules 400, the noise in any single RX band of the conventional phasedarray system will therefore also be higher than in any RX band of aphased array system constructed from the UTR modules 400.

FIG. 13 illustrates how a UTR module 400 can be configured for operationin a communications phased array system that operates according to theTDMA channel access method or utilizes time division duplexing (TDD). Incommunications systems that operate according to TDMA and other timedivision methods, transmitting and receiving occur at different times.Accordingly, the TX/RX switch 416 of the UTR module 400 is set to the TXposition during the time slot during which the UTR module 400 istransmitting and is set to the RX position during times the UTR module400 is receiving. During times when the UTR module 400 is transmitting,the TX/RX switch 416 disconnects the receive path 404 from the antennaelement 406, preferably connecting the receive path 404 to ground. Ifadditional isolation beyond that provided by the TX/RX switch 416 isneeded, the BPF 418 in the receive path can be off-tuned duringtransmitting. The remaining components of the UTR module operate similarto as describe above.

It should be mentioned that the TX/RX switch 416 of the UTR module couldalternatively be configured outside the receive path 400 and at theantenna element 406 termination point, and operated so that italternately switches the antenna element termination between thetransmit path 402 (during transmitting) and receive path 404 (duringreceiving). While that alternative approach would allow the UTR module400 to operate in a communications system that uses time divisioncommunications, such as in FIG. 13, it would not allow full-duplexoperations, like described in FIG. 12 above. Accordingly, in order toextend the universality of the UTR module 400 and enhance itsmulti-purpose capabilities when deployed in a phased array, the TX/RXswitch 416 of the UTR module 400 is disposed in its receive path 404, asshown in FIGS. 4, 12, 13 and other drawings of this disclosure.

FIG. 14 is a system level drawing of a communications phased arraysystem 1400, according to an embodiment of the present invention. Thecommunications phased array system 1400 comprises a plurality of UTRmodules 400 (similar to as shown and described above in reference toFIG. 4); an array control bus 1402; a TX/RX switch controller 1404; aplurality of RF downconverters 1406; a receiver local oscillator (RX-LO)1408; a plurality of demodulators 1410; a baseband local oscillator(BB-LO) 1412; a combiner 1414; a phase modulator 1416; and a pluralityof voltage controlled oscillators 1418.

The array control bus 1402 is configured to direct individual andindependently controllable transmit-path phase-shift control signalsφ_(TX) to the transmit-path phase shifters 414 in the UTR modules 400;individual and independently controllable receive-path phase-shiftcontrol signals φ_(RX) to the receive-path phase shifters 422;individual and independently controllable gain control signals forsetting the gains G of the LNAs 420 in the UTR modules 400, and DPScontrol signals to the DPS control inputs ρ of the DPSs 412 in the UTRmodules 400. If directed communications is not being performed, thetransmit-path phase-shift control signals φ_(TX), receive-pathphase-shift control signals φ_(RX), and LNA gain control signals are setto desired values and then not adjusted thereafter. If directedcommunications is being performed, the array control signals may beadjusted during receiving and transmitting, in order to alter thetransmit beam angle and adjust that RX array pattern. The DPS controlsignals may all be the same or each may be independently controllable,for example, to individually set (and adjust, if applicable) the outputpowers of the SMPAs 408 in each of the UTR modules 400, and may or maynot include (depending on the application) an information bearing ornon-information-bearing signal envelope. The TX/RX switch controller1404 is provided to control the ON/OFF status of the TX/RX switches 416in the UTR modules 400.

In preparing for receiving, the TX/RX switch controller 1404 in thecommunications phased array system 1400 directs the TX/RX switches 416in the UTR modules 400 to set to their RX positions, if they are notalready switched to the RX positions. The antenna elements 406 of theUTR modules 400 then transduce the RF electromagnetic waves theyintercept into a plurality of electrical received RF signals. Theplurality of received RF signals is directed to the receive paths 404 ofthe UTR modules 400, via their TX/RX switches 416, to the inputs of theBPFs 418. The BPF 418 in each UTR module 400 is tuned (eitherdynamically or tuned beforehand) to the intended RX frequency, andfurther serves to filter out any TX reflected signals or any reversesignals undesirably received from other UTR modules 400 which mightotherwise be directed into the UTR module's LNA 420. The LNA 420 in eachof the UTR modules 400 then amplifies its respective received RF signaland, if applicable, the receive-path phase shifters 422 in the UTRmodules 400 individually introduce unique phase shifts in theirrespective received RF signals, in accordance with the receive-pathphase shift control signals φ_(RX) provided by the array control bus1402.

After any desired or necessary phase shifting of the received RF signalshas been performed by the receive-path phase shifters 422, the receivedRF signals are downconverted to IF by the plurality of RF downconverters1406 and RX-LO 1408. The plurality of downconverted IF signals are thendemodulated and downconverted to a plurality of baseband signals by theplurality of demodulators 1410 and BB-LO 1412. (Alternatively, the RXsignals may be downconverted from RF to baseband directly, i.e., withoutfirst being downconverted to IF.) Finally, the combiner 1414 combinesthe plurality of baseband signals to form the final desired receivesignal. It should be mentioned that, whereas the plurality of RFdownconverters 1406, RX-LO 1408, plurality of demodulators 1410, andBB-LO 1412 have been shown and described as being external to the UTRmodules 400, some or all of these components can be incorporated intothe UTR modules 400 and formed on the same PCBs as the other componentsof the UTR modules 400.

When the communications phased array system 1400 is transmitting, a DPScontrol signal or a plurality of independently controlled DPS controlsignals is/are applied to the control inputs ρ of the DPSs 412 of theUTR modules 400. The single DPS control signal or plurality of differentDPS control signals is/are used to set the transmit output power and tocause the DPSs 412 to introduce envelope variations (if any) in thefinal phase-modulated RF signals produced and transmitted by the UTRmodules 400. Meanwhile, the phase modulator 1416 (or, alternatively, aplurality of different phase modulators, each dedicated to a single UTRmodule 400 transmit path 402) modulates the plurality of RF VCOs 1418 bya phase modulating (PM) signal. (Note that if a plurality of differentphase modulators is employed, each phase modulator and associated VCOmay also be included on the PCBs of the UTR modules 400.) Thephase-modulated RF signal generated by the phase modulator 1416 is splitand directed into the TX input of each of the UTR modules 400. Then, thetransmit-path phase shifter 414 in each UTR modules 400 independentlyintroduces a unique phase shift to the phase-modulated RF signal beingdirected through its transmit path 402, according to the transmit pathphase-shift control signal applied to its phase control input from thearray control bus 1402. If directed communications is being used, thetransmit path phase-shift control signals can be individually anddynamically adjusted during transmitting, in order to allow steering ofthe final communication beam produced by the plurality of antennaelements 406. The resulting phase-shifted phase-modulated RF signals inall UTR modules 400 are then directed to the inputs of their respectivedrivers 410/SMPAs 408. As directed by its driver 410, the phase-shiftedphase-modulated RF signal in each UTR module 400 switches its high-poweroutput transistor in its SMPA 408 (e.g., the high-power GaN-HEMT 522 inFIG. 5, if that implementation is used) ON and OFF, between compressedand cut-off states, while its DPS 412 modulates the drain of thehigh-power output transistor according to the DPS voltage produced byits DPS 412, thereby superimposing any signal envelope provided in theoriginal DPS control signal onto the high-power RF output signalproduced at the output of the SMPA 408. Finally, the antenna elements406 of all UTR modules 400 all transduce their final high-powermodulated RF signals into high-power modulated RF electromagnetic wavesand radiate the resulting high-power modulated RF electromagnetic wavesinto the air or space where they interfere to form a transmitcommunications beam of the desired power and direction.

It should be mentioned that although the transmit RF signals applied tothe UTR modules 400 are described in the communications phased array1400 above as being phase-modulated RF signals, that is not a necessarycondition. In some communications applications, the modulation formatused does not include phase modulation. Accordingly, it is not anecessary condition that the transmit RF signals in the communicationsphased array 1400 (or any of the other exemplary communications phasedarrays described herein) be phase modulated before being applied to thetransmit path inputs of the UTR modules 400, and will depend on theparticular communications application at hand. The same is true for theDPS control signals applied to the DPS control inputs ρ of the DPSs 412.While some modulation formats are envelope varying, some are not.Therefore, while it is possible to incorporate envelope modulation inthe DPS control signals, in order to introduce envelope modulation inthe final high-power RF transmit signal, incorporating envelopemodulation in the DPS control signals is not a necessary condition andwill, again, depend on the particular modulation format being used.

FIG. 15 is a system level drawing of a communications phased arraysystem 1500, according to another embodiment of the present invention.The communications phased array system 1500 is similar to thecommunications phased array system 1400 depicted in FIG. 14, bututilizes a single RF TX-VCO 1502 to modulate and upconvert the PM to RF.Another difference is that the communications phased array 1500 utilizesa plurality of analog-to-digital converters (ADCs) 1504 to sample thereceived IF signals by a sampling clock 1506 and produce a plurality ofdigital baseband signals, a plurality of digital demodulators 1508 todemodulate the digital baseband signals, and a digital combiner 1510 tocombine the demodulated digital baseband signals. It should be notedthat, whereas the phase modulator 1516 in the communications phasedarray system 1500 in FIG. 15 and the phase modulator 1416 in thecommunications phased array system 1400 in FIG. 14 both operate tomodulate their respective TX VCOs directly, the phase modulation couldfirst be performed at baseband or some intermediate transmit frequencyand then subsequently upconverted to RF.

FIG. 16 is a system level drawing of a communications phased arraysystem 1600, according to another embodiment of the present invention.The communications phased array system 1600 is similar to thecommunications phased array system 1500 depicted in FIG. 15, bututilizes a direct digital synthesizer (DDS) 1602 to generate thephase-modulated RF signals for the TX inputs of the UTR modules 400.FIG. 17 is a drawing showing the salient elements of a DDS 1700 that canbe used, adapted or modified to implement the DDS 1602 in thecommunications phased array system depicted in FIG. 16, as well as theDDSs used in other embodiments of the invention. The DDS 1700 comprisesan n-bit phase accumulator 1702, a read-only memory (ROM) 1704, adigital-to-analog converter (DAC) 1706, and a low-pass filter (LPF)1708. The phase accumulator 1702 is configured to update (i.e.,accumulate) on each cycle of a very high-speed clock (CLK) and storethereupon an n-bit number in its phase register 1710. Also on each cycleof the CLK, the previous value of the n-bit number stored in the phaseregister 1710 is added to a digital multiplier M, via a summer 1712. Thedigital multiplier M is determinative of the output frequency (i.e.,carrier frequency f_(c)=ω_(c)/2π) of the DDS 1602. For example, when M=0. . . 01, the phase accumulator 1702 accumulates for 2^(n) cycles of theCLK, then overflows and restarts, and the output frequency is equal toω_(c)=2πf_(CLK)/2^(n). When M is greater than 0 . . . 01, the phaseaccumulator 1702 rolls over M times as fast and the output frequency isequal to ω_(c)=Mπf_(CLK)/2^(n). Digital PM provided by a basebandprocessor (not shown) is introduced via a summer 1714 that is disposedin the signal path between the output of the phase accumulator 1702 andthe input of the ROM 1704. The resulting digital phase-modulated signal,produced at the output of the summer 1714, serves as an address to acosine lookup table (LUT) stored in the ROM 1704. Each addressable entryin the LUT maps to a phase point on a cosine wave from 0 to 2π radians(i.e., 0° to 360°). Therefore, the cosine LUT serves as aphase-to-amplitude converter, directly mapping the phase information inthe digital phase-modulated signal into a sequence of digital amplitudewords. The digital amplitude words are then converted to an analogwaveform by the DAC 1706 and low-pass filtered by the LPF 1708, toproduce the final phase-modulated RF signals for the UTR modules 400.

FIG. 18 is a system level drawing of a communications phased arraysystem 1800, according to another embodiment of the present invention.According to this approach, a plurality of DDSs 1802 is employed. EachDDS 1802 of the plurality of DDSs is dedicated to a single transmit path404 of an associated UTR module 400. The phase-modulated signalsproduced by the plurality of DDSs 1802 are upconverted to RF by aplurality of upconverters 1804 and a TX-LO 1806. The resulting pluralityof phase-modulated RF signals are then directed to the TX inputs of theplurality of UTR modules 400, where they are then individuallyphase-shifted by the transmit-path phase shifters 414 (and dynamicallyadjusted if directed communications is being used) in the transmit paths402 of the UTR modules 400. After phase shifting, the signals areamplified by the SMPAs 408, to produce a plurality of high-powerphase-shifted RF transmits signals, similar to as described above. Whenthe system 1800 is receiving, the TX/RX switch controller 1404 directsthe TX/RX switches 416 in the UTR modules 400 to set to their RXpositions, if not already set to their RX positions. The antennaelements 406 of the UTR modules 400 then transduce the RFelectromagnetic waves that they intercept into a plurality of receivedRF electrical signals. The plurality of received RF signals is thendirected to the receive paths 404 of the UTR modules 400, via theirTX/RX switches 416, to the inputs of their BPFs 418. The BPF 418 in eachUTR module 400 is tuned to the intended RX frequency, thereby serving topass the intended RF received signals. The BPF 418 in each UTR module400 further serves to filter out any TX reflected or reverse signalsinadvertently received from other UTR modules that might otherwise bedirected into the LNA 420 in its receive path 404. The LNAs 420 in theUTR modules 400 then amplify their respective received RF signals and,if applicable, the receive-path phase shifters 422 individuallyintroduce phase shifts Δφ_(RX) in their respective received RF signals,in accordance with the receive-path phase-shift control signals φ_(RX)provided via the array control bus 402. The signals are thendownconverted to IF by the plurality of RF downconverters 1406 and RX-LO1408, downconverted to digital baseband signals by the ADCs 1504 andsampling clock 1506, demodulated by the plurality of digitaldemodulators 1508, and then combined by a digital combiner 1808, to formthe desired received signal. It should be noted that whereas the RFupconverters 1804, TX-LO 1806, RF downconverters 1406, RX-LO 1408, ADCs1504, and digital demodulators 1508 are shown in FIG. 18 as beingexternal to the UTR modules 400, some or all of those components can beincluded on the UTR modules' PCBs. The same is true for other similarembodiments of the invention.

FIG. 19 is a system level drawing of a communications phased arraysystem 1900, according to another embodiment of the present invention.In this approach, during transmission a single DDS 1902 generates adigital phase-modulated signal at baseband or some intermediatefrequency. A digital beamformer 1904 splits the digital phase-modulatedsignal into a plurality of independent digital phase-modulated signals,which are then converted to analog waveforms by a plurality of DACs1904, and subsequently upconverted to RF by the plurality ofupconverters 1804 and a TX-LO 1806, similar to as in the communicationsphased array system 1800 shown and described above in reference to FIG.18. The digital beamformer 1904 also serves to individually set andcontrol the transmit-path phase shifts of the signals transmitted by theUTR modules 400′, rather than employing the transmit-path phase-shifters414 in the UTR modules 400′, and individually sets and controls thereceive path phase shifts of the signals received by the UTR modules400′, once the received signal have been downconverted to baseband anddemodulated, rather than using the receive-path phase-shifters 422.Because the digital beamformer 1904 in this embodiment of the inventionis used to set and control the phase shifting of the transmitted andreceived signals, the transmit-path phase and receive-path phaseshifters 414 and 422 in the UTR modules are not needed. Accordingly, theUTR modules of the communications phased array system 1900 in FIG. 19are labeled using the indicator 400′, rather than the indicator 400, toindicate that the UTR modules 400′ have a slightly different design (notransmit-path and receive-path phase shifter 414 and 422) compared tothe design of the UTR module 400 in FIG. 4. It should be mentioned thatthe UTR modules 400′ could be designed to still include thetransmit-path phase and receive-path phase shifters 414 and 422, and ifso equipped, they, together with the digital beamformer 1904, could beused to set and control the phase shifts of the transmitted and receivesignals. The digital beamformer 1904 may be further configured tocontrol the relative amplitudes of the transmitted and received signals,either by itself or in combination with the gain control signals appliedto the LNAs 420 (during receiving) and the DPS control signals appliedto the control inputs ρ of the DPSs 412 (during transmitting).

FIG. 20 is a drawing of a multi-purpose communications phased arraysystem 2000, according to another embodiment of the present invention.The multi-purpose communications phased array system 2000 includes afirst sub-array 2002, which is used for a first communicationsapplication, and a second sub-array 2004 that operates independently ofthe first sub-array 2002 and is used for a second communicationsapplication. The distinction between the “first communicationsapplication” an “second communications” application may refer to, forexample, first and second modulating schemes, first and secondcommunications standards, first and second communications protocols,first and second channel access methods, first and second duplexingmethods, or any other communications-related distinction.

When the first sub-array 2002 is preparing for transmitting, the TX/RXswitch controller 1404 directs the TX/RX switches of the UTR modules 400in the first sub-array 2002 to set to their TX positions. A first DDS12006 associated with the first sub-array 2002 (or a first plurality ofDDSs, similar to as in FIG. 18) then generates a first plurality ofphase-modulated signals based on a first digital phase modulating signalPM1 (if the modulation format being used in the first sub-array 2002includes phase modulation). The first plurality of phase-modulatedsignals is then upconverted to RF (if not previously upconverted to RFdirectly) and applied to the transmit inputs of the UTR modules 400 inthe first sub-array 2002. The transmit-path phase shifter 414 in each ofthe first sub-array's UTR modules 400 independently introduces a uniquephase shift to the phase-modulated RF signal being directed through itstransmit path 402, according to a corresponding transmit pathphase-shift control signal applied to the phase control input of thetransmit-path phase shifter 414 from a first sub-array control bus 2008.If directed communications is being used, the transmit path phase-shiftcontrol signals can be dynamically adjusted as the first sub-array 2002is transmitting, in order to steer the final communication beam producedby the plurality of antenna elements 406 in the first sub-array 2002.The resulting phase-shifted phase-modulated RF signals in the transmitpaths 402 of all of the first sub-array 2002 UTR modules 400 are thendirected to the inputs of their respective drivers 410/SMPAs 408.Similar to as explained above, the driver 410 in each UTR module of thefirst sub-array 2002 switches the high-power output transistor of itsassociated SMPA 408 ON and OFF, between compressed and cut-off states,while its DPS 412 varies or modulates the drain of the high-power outputtransistor according to the DPS voltage produced by its DPS 412, therebysuperimposing any signal envelope information that may be present in thefirst DPS control signal (DPS control 1 in FIG. 20) onto the high-powerRF output signal produced at the output of the UTR module's SMPA 408.The DPS control signals can also be used to individually set and adjustthe output powers produced by the SMPAs 408 in the first sub-array 2002.Finally, the antenna elements 406 of all UTR modules 400 in the firstsub-array 2002 transduce their final high-power amplitude and phasemodulated RF signals into high-power modulated RF electromagnetic wavesand radiate the resulting high-power modulated RF electromagnetic wavesinto the air or space, where they interfere to form a first sub-arraytransmit communications beam of the desired power and direction.

Transmitting by the second sub-array 2004 is performed similarly butseparately from the first sub-array 2002. It should be mentioned thatthe demarcation between the first and second sub-arrays 2002 and 2004may be a physical division of the array (for example, by dividing theUTR modules array into first and separate sub-arrays in which eachsub-array has adjacent UTR modules) or may be a logical division inwhich the UTR modules making up the first and second sub-arrays 2002 areeach electronically selected such that the UTR modules making up thefirst sub-array 2002 are not necessarily adjacent to one another and theUTR modules making up the second sub-array 2004 are also not necessarilyadjacent to one another. Whether physically or logically divided, whenthe second sub-array 2004 is preparing for transmitting, the TX/RXswitch controller 1404 directs the TX/RX switches 416 of the UTR modules400 in the second sub-array 2004 to set to their TX positions. A secondDDS2 2010 associated with the second sub-array 2004 (or a secondplurality of DDSs, similar to as in FIG. 18) then generates a secondplurality of phase-modulated signals using a second digital phasemodulating signal PM2 (if the modulation format being used in the secondsub-array 2004 includes phase modulation). The second plurality ofphase-modulated signals is then upconverted to RF (if not previouslyupconverted to RF directly) and applied to the transmit inputs of theUTR modules 400 in the second sub-array 2004. The transmit-path phaseshifters 414 in each UTR module 400 of the second sub-array 2004 thenindependently introduces a unique phase shift to the phase-modulated RFsignal being directed through its transmit path 402, according to acorresponding transmit path phase-shift control signal applied to thephase control input of the transmit-path phase shifter 414 from a secondsub-array control bus 2012. If directed communications is being used inthe second sub-array 2002, the transmit path phase-shift control signalscan be dynamically adjusted as the second sub-array 2004 istransmitting, in order to steer the final communication beam produced bythe plurality of antenna elements 406 in the second sub-array 2004. Theresulting phase-shifted phase-modulated RF signals in all of the secondsub-array 2004 UTR modules 400 are then directed to the inputs of theirrespective drivers 410/SMPAs 408. Similar to as explained above, thedriver 410 in each UTR module of the second sub-array 2002 switches thehigh-power output transistor of its SMPA 408 ON and OFF, betweencompressed and cut-off states, while its DPS 412 varies or modulates thedrain of the high-power output transistor according to the DPS voltageproduced by its DPS 412, thereby superimposing any signal envelopeinformation that may be present in the second DPS control signal (DPScontrol 2 in FIG. 20) onto the high-power RF output signal produced atthe output of the UTR module's SMPA 408. Finally, the antenna elements406 of all UTR modules 400 in the second sub-array 2004 transduce theirfinal high-power modulated RF signals into high-power modulated RFelectromagnetic waves and radiate the resulting high-power modulated RFelectromagnetic waves into the air or space, where they interfere toform a second sub-array transmit communications beam of the desiredpower and direction.

When the first sub-array 2002 is preparing for receiving, the TX/RXswitch controller 2005 directs the TX/RX switches 416 in the UTR modules400 of the first sub-array 2002 to set to their RX positions, if theyare not already switched to their RX positions. The antenna elements 406of the UTR modules 400 in the first sub-array 2002 then transduce the RFelectromagnetic waves they intercept into a first plurality ofelectrical received RF signals. The first plurality of received RFsignals is directed to the receive paths 404 of the UTR modules 400 ofthe first sub-array 2002, via their TX/RX switches 416, to the inputs oftheir BPFs 418. The BPF 418 in each UTR module 400 of the firstsub-array 2002 is tuned (either dynamically or tuned beforehand) to theintended RX frequency of the first sub-array 2002, and further serves tofilter out any TX reflected or reverse signals received from other UTRmodules 400 that might otherwise be directed into the LNAs 420 in itsreceive path 404. The LNAs 420 in the UTR modules 400 of the firstsub-array 2002 then amplify their respective received RF signals and, ifapplicable, the receive-path phase shifters 422 individually introduceunique phase shifts in their respective received RF signals, inaccordance with the receive-path phase-shift control signals providedover the first sub-array control bus 2008. The gains G1 of the LNAs 420in the first sub-array 2002 can also be adjusted to affect the RXpattern of the signal received by the first sub-array 2002. After anynecessary phase shifting of the received RF signals has been performedby the receive-path phase shifters 422, the received RF signals in thefirst sub-array 2002 are downconverted to IF by a first plurality of RFdownconverters 2014 and a first sub-array RX-LO1 2016. A first pluralityof ADCs 2018 then samples the received IF signals according to a firstsub-array sampling clock 2020 at a baseband frequency, and a firstplurality of digital demodulators 2032 then demodulates thedownconverted digital signals and introduces them to a digital combiner2024, which finally combines the baseband signals to form the finaldesired first sub-array 2002 receive signal.

Receiving by the second sub-array 2004 is performed independent of thefirst sub-array 2002. When the second sub-array 2004 is preparing forreceiving, the TX/RX switch controller 2005 directs the TX/RX switches416 of the UTR modules 400 in the second sub-array 2004 to set to theirRX positions, if they are not already in the RX positions. The antennaelements 406 of the UTR modules 400 in the second sub-array 200 thentransduce the RF electromagnetic waves they intercept into a secondplurality of electrical received RF signals. The second plurality ofreceived RF signals is directed to the receive paths 404 of the UTRmodules 400 of the second sub-array 2004, via their TX/RX switches 416,to the inputs of their BPFs 418. The BPF 418 in each UTR module 400 ofthe second sub-array 2004 is tuned (either dynamically or tunedbeforehand) to the intended RX frequency of the second sub-array 2004,and further serves to filter out any TX reflected or reverse signalsreceived from other UTR modules that might otherwise be directed intothe LNAs 420 in its receive path 404. The LNAs 420 in the UTR modules400 then amplify their respective received RF signals and, ifapplicable, the receive-path phase shifters 422 individually introduceunique phase shifts in their respective received RF signals, inaccordance with the receive-path phase-shift control signals providedover the second array control bus 2012. The gains G2 of the LNAs 420 canalso be adjusted to affect the RX pattern of the signal received by thesecond sub-array 2004. After any necessary phase shifting of thereceived RF signals has been performed by the receive-path phaseshifters 422, the received RF signals in the second sub-array 2004 aredownconverted to IF by a second plurality of RF downconverters 2026 anda second sub-array RX-LO2 2028. A second plurality of ADCs 2030 thensamples the received IF signals according to a second sub-array samplingclock 2032 at a baseband frequency, and a second plurality of digitaldemodulators 2034 then demodulates the downconverted digital signals andintroduces them to the digital combiner 2024, which finally combines thebaseband signals to form the final desired second sub-array 2004 receivesignal.

Because the first and second sub-arrays 2002 and 2004 operateindependently from one another, simultaneous communications according todifferent channel access methods, different modulation schemes,different communications standards, etc. is possible. For example, thefirst sub-array 2002 can be configured and controlled to operate in afull-duplex system (similar to as described above in reference to FIG.12) while the second sub-array 2004 is operating in a communicationssystem that uses the TDMA channel access method. The first sub-array2002 could also be used for non-steered communications while the secondsub-array 2004 is being used for communications that are adaptive andallow the second sub-array 2004 transmit communications beam to be aimedand steered.

In the multi-purpose communications phased array system 2000 in FIG. 20,simultaneous communications according to different communicationsapplications is possible. The wideband agility of the SMPA 408,tunability of the BPFs 418, and controllability of the TX/RX switches416 in the UTR modules 400 also affords the ability to employ a singlephased array for first and second communications applications over time.In other words, any one of the communications phased array systemsdescribed in FIGS. 14, 15, 16 and 18 above (or other single phased arraysystem employing the UTR modules 400) can be configured for use in afirst communications application and then subsequently reconfigured foruse in a second communications application. For example, the UTR modules400 in any one of those communications phased array systems could befirst configured for full-duplex operations (similar to discussed abovein reference to FIG. 12) and then reconfigured very rapidly (ifnecessary), even on-the-fly, for time division communications (similarto discussed above in reference to FIG. 13). Thisconfiguration/reconfiguration capability could also be combined with thesimultaneous communications capability of the multi-purposecommunications phased array system 2000 in FIG. 20, thereby allowingfirst and second sub-arrays to operate simultaneously according to firstand second communications applications and allowing a third sub-array tobe configured and reconfigured over time, in order to accommodate thirdand fourth communications applications.

In addition to the ability of the UTR modules 400 of the presentinvention to being well-suited for communications applications, they arealso well-suited for radar applications. FIG. 21 illustrates, forexample, how one of the UTR modules 400 can be configured for use in aradar phased array system. In radar phased arrays, a high-frequency RFsource (or “exciter”) generates low-power, high-frequency RF pulses thatare converted into high-power, high-frequency RF pulses. The high-power,high-frequency RF pulses are directed toward a target (for example, aship, aircraft, guided missile, spacecraft, motor vehicle, weatherformation, etc.), upon which they reflect. The reflected RF pulses andtheir time of flight back to the array allow the target to be identifiedand its location, direction and speed to be tracked.

When the UTR module 400 is deployed in a radar phased array and the UTRmodule 400 is transmitting, the TX/RX switch 416 in the receive path 404of the UTR module 400 (see FIG. 21) is set to the TX position, in orderto isolate the receive path 404. (If additional isolation is neededduring transmitting, the BPF 418 can be off-tuned to further isolate thereceive path 404.) Once the TX/RX switch 416 is set to the TX position,high-frequency RF pulses from the RF source (not shown in FIG. 21) aredirected into the transmit path 402 of the UTR module 400. The phaseshift Δφ_(TX) introduced into the transmit path 402 by the transmit-pathphase shifter 414 is set and controlled by the transmit path phase-shiftcontrol signal φ_(TX) applied to the phase control input of thetransmit-path phase shifter 414. When the UTR module 400 is deployed ina radar phased array system, the phase shifts introduced into thetransmit paths 404 by the transmit-path phase shifters 414 in the otherUTR modules 400 of the array are also individually set and controlled,so that collectively the phase shifts introduced into the transmit paths402 of the UTR modules 400 in the array define the direction oftransmission of the pulsed radar beam radiated by the array's antennaelements 406. If the pulsed radar beam must be steered duringtransmission, which is normally the case, transmit path phase-shiftcontrol signal applied to the transmit-path phase shifters 414 in eachUTR module can also be used to individually and dynamically adjust thephase shift introduced into each of the transmit paths 402 of the UTRmodules 400. The DPS control signal applied to the control input ρ ofthe DPS 412 is used to set the transmit power of the UTR module 400.

To receive the signal reflected from the target, the TX/RX switch 416 inthe UTR module 400 is set to the RX position, as are the TX/RX switches416 in the other UTR modules 400, and the BPF 418 is tuned to theintended RX frequency of the incoming reflected radar pulses. Thecomponents in the transmit path 402 (particularly the SMPA 408 and DPS412) may also be turned off during receiving, in order to conserve powerand further isolate the transmit path 402 from the receive path 404. Thereceive path phase-shift control signals applied to the receive-pathphase shifter 422 in the array's UTR modules 400 can also beindividually and dynamically adjusted during receiving, allowing thereceived array pattern to be dynamically varied and thereby establishinga desired or required receive array pattern. The gains G of the LNAs 420in the UTR modules 400 may also be adjusted to affect the receive arraypattern.

FIG. 22 is a system level drawing further illustrating how the UTRmodules 400 can be configured in a radar phased array system 2200,according to an embodiment of the present invention. When the radarphased array system 2200 is preparing for transmitting, the TX/RX switchcontroller 2204 directs the TX/RX switches 416 in the UTR modules 400 toset to their TX positions. An RF source 2206 then provides low-power,high-frequency RF pulses to the transmit paths 402 of the UTR modules400. An array control bus 2202 further provides a plurality of differenttransmit-path phase control signals φ_(TX), which uniquely set andcontrol the phase shifts introduced by the transmit-path phase shifters414 in the plurality of UTR modules 400, and a plurality of differentDPS control signals, which are applied to the control inputs ρ of theDPSs 412 in the UTR modules 400. Alternatively, the same DPS controlsignal can be applied to all of the UTR modules 400. The phase shiftsindividually introduced to the RF pulses in the transmit paths 402 ofthe UTR modules collectively determine the direction of transmission ofthe final pulsed RF radar beam, and can be dynamically adjusted, asexplained above, to steer the pulsed radar beam, during transmission.The DPS control signals applied to the DPS control inputs ρ of the DPSs412 in the UTR modules determine the RF output power of the SMPAs 408and can be individually adjusted to affect the aperture profile of thepulsed RF radar beam, for example, to affect the shape of the main lobethe beam, suppress side lobes, and/or control null placement.

When the radar phased array 2200 is receiving, the array control bus2202 provides a plurality of different receive-path phase shift controlsignals, which are used to control the receive path phase shifters 422and thereby uniquely set and control each phase shift introduced by eachreceive-path phase shifter to the RF pulses being directed through itsassociated receive path 404. As mentioned above, the receive-path phaseshifters 422 can be dynamically adjusted during transmitting, in orderto adjust the receive array pattern to a desired or require receivearray pattern. During receiving, the array control bus also provides aplurality of gain control signals, which are applied to the gain controlinputs of the LNAs 420 in the UTR modules 400, and which can also beadjusted during transmitting to further affect the receive arraypattern. After being filtered by the BPFs 418, amplified by the LNAs420, and phase-shifted by the receive-path phase shifters 422, thesignals are downconverted to IF by a plurality of RF downconverters 2208and a RX-LO 2210, and then converted to baseband digital signals by aplurality of ADCs 2212 and a sampling clock 2214. Finally the digitalbaseband signals are combined by a digital combiner 2216, to produce thedesired received signal (i.e., the desired signal reflected from thetarget). (If the received RF pulses include modulation information,which they can in certain applications, the downconverted signals arealso demodulated before being introduced into the digital combiner2216.) The received signal may then be processed by a digital signalprocessor (DSP) 2218 and directed to an indicator 2220, where thereceive array pattern can be displayed for human viewing. It should benoted that whereas the RF downconverters 2208, RX-LO 2210, ADCs 2212 andsampling clock 2214 are shown to be external to the UTR modules 400,some or all of those components can be included on the same PCBs 802 asthe other components of the UTR modules 400. It should also be notedthat whereas the radar phased array system 2200 is shown to employ asingle low-power RF source 2206, a plurality of different low-power RFsources can be used, instead, with each RF source dedicated to one ofthe transmit paths of the UTR modules 400. The RF sources could also beincluded on the PCBs 802 of the UTR modules 400.

FIG. 23 is a system level drawing of a radar phased array system 2300,according to another embodiment of the present invention. Thisembodiment of the invention is similar to the radar phased array 2200depicted in FIG. 22 but employs a beam control computer 2302 to controlthe transmit path and receive-path phase shifts and amplitudes of thetransmitted and received signals using a plurality of phase shifters2304 (fixed or adjustable) and a plurality of attenuators 2306 (fixed oradjustable) that are external to the UTR modules 400, instead of usingthe transmit-path and receive path phase shifters 414 and 422 in the UTRmodules 400 to adjust the phases of the transmitted and received signalsand instead of using the DPSs 412 and the DPSs 412 to set and controlthe amplitudes of the transmitted and received signals. (Alternatively,a beamformer configured for operation at baseband or some intermediatefrequency could be used, rather than performing the phase and magnitudeadjustments of the transmit and receive signals, similar to thecommunications phased array system describe in reference to FIG. 19above.) Using this approach, the UTR modules 400 can be designed withoutthe transmit-path and receive path phase shifters 414 and 422 andwithout adjustable-gain LNAs 420. Alternatively, the beam controlcomputer 2302, plurality of phase shifters 2304, and plurality ofattenuators 2306 (or the beamformer, if it is used, instead) can be usedin conjunction with the phase-shifting and amplitude controllingcapabilities of the UTR modules 400. It should be again noted thatwhereas the RF downconverters 2208, RX-LO 2210, ADCs 2212, and samplingclock 2214 are shown to be external to the UTR modules 400, some or allof those components can be included on the same PCBs 802 as the othercomponents of the UTR modules 400. Furthermore, whereas only a single RFsource 2206 is employed in the radar phased array 2300, again, aplurality of different RF sources can be used for each transmit path,instead, and each RF source can be, though not necessarily, included onthe PCB 802 of its associated UTR module 400.

The versatility and wideband agility of the UTR modules 400 also affordsthe ability to use a single radar phased array for multiple radarapplications. FIG. 24 is a drawing of a multi-purpose radar phased arraysystem 2400, according to another embodiment of the present invention.The multi-purpose radar phased array system 2400 includes a firstsub-array 2402 that is used for a first radar application and a secondsub-array 2404 that is used for a second radar application. Thisembodiment of the invention can be useful in circumstances wheremultiple moving objects are involved. For example, the first and secondsub-arrays 2402 and 2404 can be used to track first and second movingtargets simultaneously, or the first sub-array 2402 could be used totrack a target (for example, an enemy airplane or ship) while the secondsub-array 2404 is being used to guide a missile toward the target.

When the first sub-array 2402 is preparing for transmitting, the TX/RXswitch controller 2405 directs the TX/RX switches 416 of the UTR modules400 in the first sub-array 2402 to set to their TX positions. A first RFsource 2406 associated with the first sub-array 2402 (or, alternatively,a first plurality of RF sources dedicated to each of the transmit pathsof the UTR modules 400 in the first sub-array 2402) generates a firstplurality of RF pulses (which may or may not be modulated withinformation). The first plurality of RF pulses is upconverted to RF (ifnot previously upconverted to RF directly) and applied to the transmitpaths 402 of the UTR modules 400 in the first sub-array 2402. The phaseshifts introduced into the transmit paths 404 by the transmit-path phaseshifters 414 in the UTR modules 400 in the first sub-array 2402 areindividually set and uniquely controlled by a plurality of transmit-pathphase shift control signals provided over a first sub-array control bus2408. The phase shifts introduced into the transmit paths 402 by all UTRmodules 400 in the first sub-array 2402 define the direction oftransmission of the pulsed radar beam radiated by the first sub-array'santenna elements 406. If the final first sub-array pulsed radar transmitbeam must be steered during transmission, which is normally the case,the transmit-path phase shifters 414 can be individually and dynamicallyadjusted during transmission. The resulting phase-shifted RF pulses inall of the first sub-array 2402 UTR modules 400 are then directed to theinputs of their respective drivers 410/SMPAs 408. The driver 410 in eachUTR module 400 of the first sub-array 2402 switches the high-poweroutput transistor of its associated SMPA 408 ON and OFF, betweencompressed and cut-off states, while its DPS 412 varies the DPS voltageapplied to the drain of the high-power output transistor of theassociated SMPA 408, according to the DPS voltage produced by UTRmodule's DPS 412. Varying the DPS voltage according to the DPS controlsignal allows the transmit powers of the UTR modules 400 in the firstsub-array 2402 to be set and adjusted during transmitting. Finally, theantenna elements 406 of all UTR modules 400 in the first sub-array 2402transduce their final high-power RF pulses into high-powerelectromagnetic-wave RF pulses and radiate the resulting high-powerelectromagnetic-wave RF pulses into the air or space, where theyinterfere to form a first sub-array pulsed radar transmit beam of thedesired power and direction.

When the second sub-array 2402 is preparing for transmitting, the TX/RXswitch controller 2405 directs the TX/RX switches 416 of the UTR modules400 in the second sub-array 2402 to set to their TX positions. A secondRF source 2410 associated with the second sub-array 2404 (or,alternatively, a second plurality of RF sources dedicated to each of thetransmit paths of the UTR modules 400 in the second sub-array 2404)generates a second plurality of RF pulses (which may or may not bemodulated with information). The second plurality of RF pulses is thenupconverted to RF (if not previously upconverted to RF directly) andapplied to the transmit paths 402 of the UTR modules 400 in the secondsub-array 2404. The phase shifts introduced into the transmit paths 404by the transmit-path phase shifters 414 in the UTR modules 400 in thesecond sub-array 2404 are individually set and uniquely controlled by aplurality of transmit-path phase shift control signals provided over asecond sub-array control bus 2412. The phase shifts introduced into thetransmit paths 402 by all UTR modules 400 in the second sub-array 2404define the direction of transmission of the pulsed radar beam radiatedby the second sub-array's antenna elements 406. If the final secondsub-array pulsed radar transmit beam must be steered duringtransmission, the transmit-path phase shifters 414 can be individuallyand dynamically adjusted during transmission. The resultingphase-shifted RF pulses in all of the second sub-array 2404 UTR modules400 are then directed to the inputs of their respective drivers410/SMPAs 408. The driver 410 in each UTR module 400 of the secondsub-array 2404 switches the high-power output transistor of itsassociated SMPA 408 ON and OFF, between compressed and cut-off states,while its DPS 412 varies the DPS voltage applied to the drain of thehigh-power output transistor of the associated SMPA 408, according tothe DPS voltage produced by the DPS 412. Varying the DPS voltageaccording to the DPS control signal allows the transmit powers of theUTR modules 400 in the second sub-array 2404 to be set and adjustedduring transmitting. Finally, the antenna elements 406 of all UTRmodules 400 in the second sub-array 2404 transduce their finalhigh-power RF pulses into high-power electromagnetic-wave RF pulses andradiate the resulting high-power electromagnetic-wave RF pulses into theair or space, where they interfere to form a second sub-array pulsedradar transmit beam of the desired power and direction.

During times when the first sub-array 2402 is receiving, the TX/RXswitches 416 in the UTR modules 400 of the first sub-array 2402 are setto their RX positions. The antenna elements 406 of the UTR modules 400in the first sub-array 2402 then transduce the RF electromagnetic wavesthey receive from a first target into a first plurality of electricalreceived RF signals. The first plurality of received RF signals isdirected to the receive paths 404 of the UTR modules 400 of the firstsub-array 2402, via their TX/RX switches 416, to the inputs of theirBPFs 418. The BPF 418 in each UTR module 400 of the first sub-array 2402is tuned (either dynamically or tuned beforehand) to the intended RXfrequency of the first sub-array 2402, and further serves to filter outany TX reflected or reverse signals received from other UTR modules 400that might otherwise be directed into the LNAs 420 in its receive path404. The LNAs 420 in the UTR modules 400 of the first sub-array 2402then amplify their respective received RF signals and the receive-pathphase shifters 422 individually introduce unique phase shifts in theirrespective received RF signals, in accordance with the receive-pathphase-shift control signals provided over the first sub-array controlbus 2408. The phase shifts introduced by the receive-path phase shiftersin the receive paths 404 of the UTR modules in the first sub-array 2402can also be dynamically adjusted during receiving, in order to alter thereceive array pattern of the first sub-array 2402 and establish adesired or required receive array pattern. The gains G1 of the LNAs 420in the first sub-array 2402 can also be adjusted to affect the receivearray pattern of the first sub-array 2402. After any desired ornecessary phase shifting of the received RF signals has been performedby the receive-path phase shifters 422, the received RF signals in thefirst sub-array 2402 are downconverted to IF by a first plurality of RFdownconverters 2414 and a first sub-array RX-LO1 2416. A first pluralityof ADCs 2418 then samples the received IF signals according to a firstsub-array sampling clock 2420, thereby producing a plurality of digitalbaseband signals. Finally, the digital baseband signals are introducedto a digital combiner 2422, which combines the baseband signals to formthe final desired first sub-array 2402 receive signal.

Receiving by the second sub-array 2404 is performed independent of thefirst sub-array 2402. When the second sub-array 2404 is receiving, theTX/RX switches 416 in the UTR modules 400 of the second sub-array 2404are set to their RX positions. The antenna elements 406 of the UTRmodules 400 in the second sub-array 2402 then transduce the RFelectromagnetic waves they receive from a second target into a secondplurality of electrical received RF signals. The second plurality ofreceived RF signals is directed to the receive paths 404 of the UTRmodules 400 of the second sub-array 2404, via their TX/RX switches 416,to the inputs of their BPFs 418. The BPF 418 in each UTR module 400 ofthe second sub-array 2404 is tuned (either dynamically or tunedbeforehand) to the intended RX frequency of the second sub-array 2402,and further serves to filter out any TX reflected or reverse signalsreceived from other UTR modules 400 that might otherwise be directedinto the LNAs 420 in its receive path 404. The LNAs 420 in the UTRmodules 400 of the second sub-array 2404 then amplify their respectivereceived RF signals and the receive-path phase shifters 422 individuallyintroduce unique phase shifts in their respective received RF signals,in accordance with the receive-path phase-shift control signals providedover the second sub-array control bus 2412. The phase shifts introducedby the receive-path phase shifters in the receive paths 404 of the UTRmodules in the second sub-array 2404 can also be dynamically adjustedduring receiving, in order to alter the receive array pattern of thesecond sub-array 2404 and establish a desired or required receive arraypattern. The gains G2 of the LNAs 420 in the second sub-array 2404 canalso be adjusted to affect the receive array pattern of the secondsub-array 2404. After any necessary or desired phase shifting of thereceived RF signals has been performed by the receive-path phaseshifters 422, the received RF signals in the second sub-array 2404 aredownconverted to IF by a second plurality of RF downconverters 2426 anda second sub-array RX-L02 2428. A second plurality of ADCs 2430 thensamples the received IF signals according to a second sub-array samplingclock 2432, thereby producing a plurality of digital baseband signals.Finally, the digital baseband signals are introduced to the digitalcombiner 2422, which combines the baseband signals to form the finaldesired second sub-array 2404 receive signal.

In the multi-purpose radar phased array system 2400 FIG. 24,simultaneous first and second radar applications is made possible byusing the first and second sub-arrays 2402 and 2404. The widebandagility of the SMPA 408, tunability of the BPFs 418, and controllabilityof the TX/RX switches 416 in the UTR modules 400 also affords theability to employ a single radar phased array system for first andsecond radar applications over time. In other words, a single radarphased array system (such as that described in reference to FIG. 22) canbe configured for use in a first radar application and then subsequentlyreconfigured for use in a second radar application. Thisconfiguration/reconfiguration capability could also be combined with thesimultaneous radar applications capability of the multi-purpose radarphased array system 2400 in FIG. 24, thereby allowing first and secondsub-arrays to operate simultaneously according to first and second radarapplications and allowing a third sub-array to be configured andreconfigured over time, in order to accommodate third and fourth radarapplications.

In some applications it is desirable or necessary for a building,facility, vehicle, or aircraft, etc. to have both radar andcommunications capabilities. Unfortunately, due to the narrowbandconstraints of conventional TR modules, two separate phased arraysystems—a first for radar and a second for communications—must be usedwhen conventional TR modules are used to build the arrays. The need todeploy multiple phased array systems in order to have both radar andcommunications capabilities is highly undesirable, particularly sincepowering multiple phased array systems requires large multiple powersupplies and large multiple cooling systems. This problem is compoundedby virtue of the fact that conventional TR modules have extremelyinefficient linear HPAs, which, as explained above, require largeheatsinks and large power supplies to compensate for the extremelyinefficient HPAs. Conventional TR modules also require large coolingsystems to displace the large amount of heat dissipated by the HPAs. Thelarge power supplies, large cooling systems, and large heatsinks notonly add substantial cost, size and weight to each TR module, they addto the overall cost, size and weight of each of the separatecommunications and radar phased array systems. These substantial SWaPperformance problems are particularly severe in situations where theseparate radar and communications phased array systems are installed inan aircraft, such as a helicopter, airplane, or satellite, or spaceprobe, for example. The separate radar and communications phased arraysystems not only takes up valuable space in the aircraft, the large andheavy power supplies and cooling systems that are needed to supply powerand cool the separate radar and communications phased array systems alsotake up valuable space and add substantial weight to the aircraft, whichadversely affects the ability to maneuver the aircraft.

The unique design and construction of the UTR module 400 of the presentinvention completely overcome the narrowband operating restriction thatplagues conventional TR modules and which prevents them from being usedin any other application but for which they are specifically designed.In contrast, the wideband agility of the UTR module 400, the superiorphase stiffness of its SMPA 408, the unique placement andcontrollability of its TX/RX switch 416, and the presence and tunabilityof its BPF 418 altogether allow a single multi-purpose phased arraysystem to be built that can be used for both radar and communications.Moreover, because the UTR module 400 employs an SMPA, and the SMPA ispreferably implemented using GaN technology, the SWaP performance of theUTR module 400 and any phased array system in which the UTR module 400is employed is substantially superior to the SWaP performance that canbe possibly realized using conventional TR modules.

FIG. 25 is a system level drawing of a multi-purpose phased array system2500 that can be used for both radar and communications applications,according to an embodiment of the present invention. The multi-purposephased array system 2500 includes a plurality of UTR modules 400configured to receive, in their transmit paths 402, either a pluralityof RF pulses from an RF source 2502 (radar application) or aphase-modulated (or unmodulated) RF communications signal generated by aDDS 2502 (communications application). When the system 2500 is beingused for radar, a comms/radar selection switch 2506 is set to the radar(R) position, and when being used for communications is set to thecommunications (C) position. (It should be mentioned that instead ofusing a single DDS 2502, single RF source 2504 and a single comms/radarselection switch 2506, a DDS, RF source and comms/radar selection switchcan be alternatively employed in each transmit paths 402. The DDS, RFsource and/or comms/radar selection switch in each transmit path couldthen be, though not necessarily, included on the same PCB as the othercomponents of their associated UTR module 400.)

When the system 250 is transmitting, a TX/RX switch controller 2508directs the TX/RX switches 416 in the UTR modules 400 to set to their TXpositions. The transmit-path phase shifter 414, DPS 412, driver 410 andSMPA 408 in each UTR module 400 then operates similar to as describedabove, to produce either high-power RF pulses (radar application) or ahigh-power modulated RF communications signal at outputs of the transmitpaths 402. The antenna elements 406 of the UTR modules 400 then converteither the high-power RF pulses or high-power RF communications signalsinto the air or space, where they interfere and combine to produceeither a radar transmit beam of the desired power and beam angle (radarapplication) communications transmit beam of the desired power and beamangle (communications application). When the system 250 is receiving,the TX/RX switches 416 in the UTR modules 400 are set to their RXpositions. The antenna elements 406 of the UTR modules 400 thentransduce the RF electromagnetic waves that they intercept (either RFpulses reflected from a target (radar application) or RF communicationssignals received from a remote transmitter) into a plurality of receivedRF electrical signals. The BPFs 418 in the UTR modules are tuned to theintended radar frequency band (radar application) or to the intendedcommunications frequency (communications application). The LNAs 420 andreceive-path phase shifters 422 in the receive paths 422 of the UTRmodules operate similar to as discussed above. The amplified andphase-shifted receive RF signals are then downconverted to IF by aplurality of RF downconverters 2510, using either a radar RX-LO 2512 ora communications RX-LO 2514, as selected by an LO selection switch 2516.The downconverted signals are then downconverted from IF to basebandusing a plurality of ADCs 2518 and sampling clock 2520, demodulated (ifnecessary) by a plurality of digital demodulators 2522, and finallycombined by a digital combiner 2524, to form the final received radar orcommunications signal. (It should be noted, that rather than employing asingle radar RX-LO 2512, single communications RX-LO 2514, and single LOselection switch 2516, a radar RX-LO, communications RX-LO, and LOselection switch can be alternatively employed in each receive path 404.The radar RX-LO, communications RX-LO, and LO switch in each receivepath 404 could then be, though not necessarily, included on the same PCBas the other components of their associated UTR module 400. Furthermore,the RF downconverter 2510, ADC 2518 and/or demodulator 2522 in eachreceive path could be, though not necessarily, included on the same PCBas the other components of their associated UTR module 400.)

The multi-purpose phased array system 2500 depicted in FIG. 25 allowsboth radar and communications applications to be performed using thesame phased array. However, it is not designed to allow radar andcommunications to be performed simultaneously. FIG. 26 is a system leveldrawing of a multi-purpose phased array system 2600 that can be used toperform radar operations and communications simultaneously, according toan embodiment of the present invention. This embodiment of the inventionalso allows two different communications applications to be performedsimultaneously (similar to as described above in reference to FIG. 20)or two different radar applications to be performed simultaneously(similar to as described above in reference to FIG. 24). Themulti-purpose phased array system 2600 comprises first and secondsub-arrays 2602 and 2604, each of which operates separately from theother. The operation of each sub-array 2602 and 2604 is similar to theoperation of the multi-phased array system 2500 depicted in FIG. 25(except for allowing simultaneous radar and communications) and theoperations of the multi-purpose communications phased array system 2000in FIG. 20 and the multi-purpose radar phased array system 2400 in FIG.24 (except for allowing both radar and communications), so need not bedescribed further, as those of ordinary skill in the art will understandits operational capabilities by referencing the descriptions of thoseand other embodiments of the invention described above.

While various embodiments of the present invention have been presented,they have been presented by way of example and not limitation. It willbe apparent to persons skilled in the relevant art that minor changes inform and detail may be made to the exemplary embodiments withoutdeparting from the true and overall spirit and scope of the invention.Accordingly, the scope of the invention should not be limited by thespecifics of the exemplary embodiments of the invention set forth abovebut, instead, should be determined by the appended claims, including thefull scope of equivalents to which such claims are entitled.

1. A universal transmit-receive (UTR) module for a phased array,comprising: a transmit path including a transmit-path delay element ortransmit-path phase shifter configured to delay or introduce a phaseshift in a low-power RF transmit signal directed along said transmitpath when said TR module is configured in a phased array to affect atransmit direction of a transmit beam produced by said phased array, adriver configured to receive a delayed low-power RF transmit signal froman output of said transmit-path delay element or a phase-shiftedlow-power RF transmit signal produced by said transmit-path phaseshifter, a switch-mode power amplifier (SMPA) having an RF input portconfigured to be driven by said driver and produce a high-power delayedor phase-shifted RF transmit signal, and a dynamic power supply (DPS)configured to generate and supply a DPS voltage to a power supply portof said SMPA while said SMPA is producing said high-power delayed orphase-shifted RF transmit signal; and a receive path including areceive-path delay element or receive-path phase shifter configured todelay or introduce a phase shift in an RF receive signal directed alongsaid receive path, to affect a receive array pattern when said TR moduleis configured in said phased array.
 2. The UTR module of claim 1,wherein said receive path further includes a switch that determineswhether said receive path is electrically coupled to or electricallyisolated from said transmit path.
 3. The UTR module of claim 1, whereinsaid receive path further includes a bandpass filter (BPF) that isconfigured to align with an intended receive frequency of a received RFsignal that is directed into said receive path, and is furtherconfigured to suppress RF transmit signals that are reflected from anantenna element during times when said receive path is electricallycoupled to said antenna element.
 4. The UTR module of claim 3, whereinsaid BPF is further configured to suppress reverse signals received byother TR modules in said phased array when said TR module is configuredin said phased array.
 5. The UTR module of claim 4, wherein said BPF istunable.
 6. The UTR module of claim 3, wherein said receive path furtherincludes a low-noise amplifier (LNA) having an adjustable gain, said LNAconfigured to amplify the received RF signal once it has been filteredby said BPF.
 7. The UTR module of claim 1, wherein said SMPA has anoutput that is configured to be directly coupled to an antenna element.8. The UTR module of claim 2, wherein said SMPA has an output that isconfigured to be directly coupled to an antenna element and the outputof said SMPA is configured to remain directly coupled to said antennaelement at all times, including during times said switch is configuredto electrically couple said receive path to said antenna element.
 9. TheUTR module of claim 1, wherein said SMPA comprises a gallium nitridebased (GaN-based) SMPA.
 10. The UTR module of claim 2, wherein saidswitch is configurable to maintain said receive path in electricalconnection with an antenna element during all times said antenna elementis radiating RF electromagnetic waves and during all times said antennaelement is capturing RF electromagnetic waves.
 11. The UTR module ofclaim 2, wherein said switch is further configurable to electricallyisolate said receive path from an antenna element during times saidantenna element is radiating RF electromagnetic waves and electricallycouple said receive path to said antenna element during times saidantenna element is capturing RF electromagnetic waves.
 12. The UTRmodule of claim 1, wherein the UTR module is configurable to performradar and alternately configurable to perform communications. 13-26.(canceled)
 27. A universal transmit-receive (UTR) module, comprising: atransmit path including a power amplifier (PA); and a receive pathincluding a switch, wherein said switch is configurable to electricallycouple and decouple said receive path to an antenna element, and said PAhas an output that remains directly coupled to the antenna element atall times, including during times said switch is configured toelectrically couple said receive path to the antenna element.
 28. TheUTR module of claim 27, where said switch is configured to alternatelycouple and decouple said receive path to and from the antenna element.29. The UTR module of claim 27, wherein said switch is configured tomaintain an electrical connection with said receive path during timesthe transmit path and antenna element are transmitting electromagneticwaves while said receive path and antenna element are receivingelectromagnetic waves.
 30. The UTR module of claim 27, wherein the UTRmodule is configurable to perform both communications and radaroperations.
 31. The UTR module of claim 27, wherein said receive pathincludes a bandpass filter that is configured to be dynamically tunedduring times said receive path and antenna element are receivingelectromagnetic waves.